public class R {
        public static void main(String args[])
        {
            double a[]={1,2};
            double b[] = new double[3];
            System.out.println("数组a的个数："+a.length);
            System.out.println("数组a的个数："+b.length);
            b[0] = 10;
            b[1] = 20;
            b[2] = 30;
            System.out.println("a[0]="+a[0]+"a[1]="+a[1]);
            System.out.println("b[0]="+b[0]+"b[1]="+b[1]+"b[2]="+b[2]);
        }
    }


